The current invention pertains generally to automotive rear lighting systems employing differently colored lights to perform different functions, and especially to rear lighting systems in which red colored light, and only red colored light, is displayed during braking, and in which non-red colored light, and only non-red colored light, can be displayed at other times. The purpose of the said color distinction is to make display of red colored light per se an unambiguous, immediately perceptible signal of braking, and thereby to reduce the incidence of rear-end automotive vehicle collision, delayed perception of the brake signal being a significant contributing factor in many of said rear-end collisions.
Various means are available by which the said color distinction can be implemented. In a previously described rear lighting system (Cameron, U.S. Pat. No. 4,661,795), spring-loaded electric switching means, actuated by actuation of brake actuation means, close electric circuits between a source of electrical energy and lamps effecting red colored light, and open electric circuits between said source of electrical energy and lamps effecting non-red colored light, said switching actions being reversed when said brake actuation means is released. Alternative means are described in patent application Ser. No. 07/066,211, said alternative comprising mechanical and electro-mechanical means whereby all light emanating toward the rear from illuminated lamps is caused to be transmitted, during braking, through material containing a red colored pigment, and further, caused to be transmitted at other times through material containing a non-red colored pigment.
The current invention employs potentiometric means to alternatively interpose high electric resistance or low electric resistance into electric circuits between a source of electrical energy and rear lamps effecting red colored light and rear lamps effecting non-red colored light, flow of energizing electric current sufficient to effect illumination of a given lamp being enabled by interposition of low electric resistance, but being prevented by interposition of high electric resistance. During braking, there is low electric resistance in electric circuits to lamps effecting red colored light, and high electric resistance in electric circuits to lamps effecting non-red colored light. When the brake actuation means is not actuated, there is high electric resistance in electric circuits to lamps effecting red colored light, and low electric resistence in electric circuits to lamps effecting non-red colored light. Thus, lamps effecting red colored light can be illuminated only during braking, and lamps effecting non-red colored light can be illuminated only when the brake actuation means is not actuated.